Lignite derivative and process for preparing the same



June 2, 1964 LIGNITE DERIVATIVE AND PROCESS FOR PREPARING THE SAMEOriginal Filed May 10, 1957 YIELD POINT 8 8 YIELD PO l NT K. P. MONROE 3Sheets-Sheet 1 lO/IO N00 H/Quebr ho S/IO NuOH/Quebruchu I 1 l I lb/bblDispersunt KENNETH P. MONROE INVENTOR.

Ib/bbl Lima FIG.2

BY AN ISM, /& F l/mA ATTORNEYS June 2, 1964 p, MQNROE 3,135,727

LIGNITE DERIVATIVE AND PROCESS FOR PREPARING THE SAME Original Filed May10, 1957 3 Sheets-Sheet 2 I I I I I I I uP-n '- z 6 raw-24 n.

so 3 E MP-23 o l I l I I o 0.5 L0 |.5 2.0 5 l0 I5 lb/bbl Disparsantlb/bbl NoCI FIG. 3

I I I I I ao-- E MP-zs O a so O ra -4o .J J

KENNETH P. MONROE I I I I l I v 2 3 4 8 INVENTOR.

lbs/bbl Dispersoni lbs/Dbl NuCl 4 FJIJM ATTORNEY S June 2, 1964LIGNI'I'E DERIVATIVE AND PROCESS FOR PREPARING THE SAME Original FiledMay 10, 1957 K. P. MONROE 3 Sheets-Sheet 5 YIELD POINT KEN NETH P.MONROE INVENTOR.

I 2 3 l 2 3 lbs/Dbl Dispersnm lbs/bbl Lime FIG. 5

I I I I I MP-I3 PAP-23" NIP-I3 I I I I l I I 2 3 l 2 5 4 Ibt/bblDispersum lba/bbl Lima FIG 6 BY ATTORNEYS United States Patent 3,135,727LIGNITE DERIVATIVE AND PROCESS FOR PREPARING THE SAME Kenneth P. Monroe,Houston, Tex, assignor to Magnet Cove Barium Corporation, Houston, Tex.,a corporation of Arkansas Original application May 10, 1957, Ser. No.658,378, now Patent No. 3,034,932, dated May 15, 1962. Divided and thisapplication Oct. 31, 1961, Ser. No. 151,59fi 22 Claims. (Cl. 260-125)This invention relates to water-soluble or water dispersible lignitederivatives and also to a well fluid in which such lignite derivativesare employed to control the properties, particularly the yield point andviscosity characteristics of the fluid. In another respect, it relatesto methods for producing such lignite derivatives. In still anotheraspect, the invention relates to a method for controlling the yieldpoint of a well fluid such as a mud.

Lignite, an abundant and cheap domestic raw material, previously hasbeen used to control the viscosity of oil well drilling muds. Itsusefulness as a thinner for muds has been limited because it is renderedmuch less effective by commonly encountered mud contaminants such ascommon salt (sodium chloride) and calcium compounds (anhydrite, gypsum,cement and the like). In other words, these mud contaminants willprogressively coagulate the lignite so that it can no longer exert itsdesired protective colloidal action.

Further, lignite is significantly effective as a viscosity control agentonly when used in conjunction with caustic or in a highly alkaline mud.One practice has been to mix raw lignite and caustic together at thewell site in order not only to solubilize the lignite but also to givethe mud the required causticity for the lignite to exert its maximumthinning effect. This requires not only handling of two separatematerials but also the handling of large amounts of caustic, which isfraught with danger. Furthermore, control in the field of thecaustic-lignite reaction and of the amount of caustic present in the mudto get optimum results are both difiicult so that treating results tendto be erratic.

Attempts have been made to pre-react lignite with caustic or soda ash soas not only to improve its usefulness as a mud thinner but also toprovide a single material which can be manufactured under controlledconditions at a central site and then shipped to the field for use as asingle additive. Such pro-reaction of raw lignite with moderate amountsof water-soluble alkali (up to and including about 25% of the weight ofthe raw lignite so pro-reacted) has been a common practice, since theresulting product can be readily manufactured as a noncaking,free-flowing powder by conventional drying methods. However, thepre-reacted product does not have the desired effectiveness as athinning agent in the presence of salt and calcium contamination becauseit will still be coagulated. To decrease the degree of coagulation, thedriller must add not only the pre-reacted lignite but also a largeamount of additional caustic (usually a weight about equal to that ofthe pro-reacted lignite). Thus the driller must still handle twoingredients including relatively large amounts of the troublesomecaustic, so that in such cases there is very little advantage in usingpre-reacted lignite in place of raw lignite other than the fact that thepro-reacted lignite can be dispersed more easily than the raw lignite.Efforts have been made to pre-react the necessary large amount ofcaustic with the lignite, but the large amount of caustic makes thecomplete removal of water from the final product very difiicult, and thefinal product, even when forcibly dried under extreme conditions, isextremely hygroscopic, cakes severely under ordinary conditions ofhandling and storage, is almost as corrosive to the skin as 3,l35 ,727Patented June 2, 1964 is pure sodium hydroxide, and is often easilyspontaneously combustible. Therefore, since pre-reaction of all therequired caustic with the lignite is not commercially feasible, the oilwell driller necessarily has to handle caustic at the wellhead eventhough he uses the pro-reacted lignite. In accordance with one aspect ofthis invention, there is provided a new and novel process in which rawlignite is reacted, in an alkaline medium, with a water-soluble sulfiteor bisulfite and an aldehyde or ketone to produce a new and novelproduct, sulfo-alkylated lignite which in turn, can be oxidized ornitritated to produce still another new and novel product, oxidized ornitritated sulioalkylated lignite.

It has been found these products can be used as a dispersing agent,particularly as a thinning and yield point controlling agent fordrilling muds. The efficiency of the sulfo-alkylated lignite is lessthan that of the oxidized or nitritated sulfo-alkylated lignite. As willbe shown, the sulfo-alkylated lignite and the oxidized form thereof areusually at least equal in dispersing power to conventionalquebracho-caustic and lignite-caustic dispersants and, in many mudsystems, particularly those containing a hydratable clay such asbentonite, they are superior to these two conventional dispersants andthis is particularly true in those systems contaminated with salt andcalcium. Through this discovery, there is provided new and novel wellfluids and methods of treating the same to control their yield pointwithout substantially adversely affecting their other characteristicssuch as gel strength and fluid loss.

The new products above referred to can be provided as dry products forcommercial use by conventional drying methods, such by drum drying,spray drying, or the like. They are stable, non-caking and free-flowingproducts when packaged, stored and transported in conventionalmulti-wall paper bags. They are readily useahle by the oil well drillerwithout additional processing, affording the driller for the first timea lignitic additive which in many systems can be used without theaddition of caustic therewith and in other systems with only smallamounts of added caustic, to yield the desired maximum yield pointcontrol of muds in the presence of commonly encountered mudcontaminants. The products are noncorrosive to the skin and are notprone toward spontaneous combustion under customary conditions ofmanufacture, storage and transport.

It is accordingly an object of this invention is provide new ligniticderivative products of the types above-mentioned and to provide aprocess for making such lignitic products, the process being directed tothe upgrading of lignite into a water-soluble form such that it will bean efiicient dispersant not requiring large quantities of caustic forits use.

Another object is to provide a process of treating lignite to convert itinto an efficient dispersing agent finding particular use in drillingmuds, the treatment involving the reaction of lignite with certainreactants in such a manner that its dispersing power is greatlyincreased without the use of large quantities of caustic so that theresulting lignitic product can be packaged, sold and used as a singleproduct which will not cake during storage and which is not noticeablycorrosive to the skin.

Another object is to provide a process wherein sulfoalkylated lignite isoxidized to further enhance its dispersing powers.

Another object is to provide a drilling mud in which a ligniticderivative of the foregoing types is employed as a dispersant to controlthe yield point of the mud, particularly when the mud is contaminatedwith salt or calcium or when it contains highly hydratable clays such asbentonite.

Another object is to provide a method for controlling the yield pointcharacteristics of a mud through the use of a lignitic reaction productof the types above mentioned.

Another object is. to provide a process for increasing the hydrophilicproperties of lignite to produce new products having various uses inaddition to those mentioned above.

Other objects, advantages and features of this invention will beapparent to one skilled in the art upon consideration of the writtenspecification and claims.

The annexed drawings represent plots of the results of certain tests setout in the examples below. In these drawings:

FIG. 1 represents a comparison of the thinning characteristics of apreferred species of this invention and conventional dispersants;

FIG. 2 represents a comparison in a lime-contaminated mud of thethinning characteristics of sulfo-alkylated lignite and conventionalalkali-lignite;

FIG. 3 is another comparison in a salt-contaminated mud;

FIG. 4 illustrates the viscosity control characteristics of variousalkali metal sulfo-methylated lignites;

- FIG. 5 illustrates the variation of effectiveness of one dispersant ofthis invention in a lime mud with varying amounts of sulfo-alkylation;and

FIG. 6 represents the difference in results which are obtained in a limemud when varying amounts of sodium hydroxide are used in preparing thesulfo-alkylated lignite of this invention. I

The sulfo-alkylated lignite of this invention can be prepared byadmixing lignite, a water-soluble alkali metal hydroxide, awater-soluble sulfite or bisulfite of an alkali metal, and an aldehydeor ketone in reaction medium and then causing inter-action between theseingredients under conditions of time and temperature which causechemical conversion of a substantial portion of the original lignite toa more hydrophylic product.

It is thought that this product is a sulfo-alkylated lignite, the termalkylated being used in its broadest sense to include aliphatic,cycloaliphatic, heterocyclic and aryl groups. If such is true, then thelignite is solubilized by adding thereto a sulfo-alkyl radical wherein Ris a methylene radical or a substituted methylene radical derived from aketone or an aldehyde and M is an alkali metal. Further where a dior apoly-ketone or -aldehyde is used, that is one containing a plurality ofketo or aldo, or both, groups per molecule, the two methylene groupswill be linked together by the remainder of the ketone or aldehydemolecule, there being present two -SO M groups and the methylene groupsbeing connected to one or more lignite molecules. However, due to thechemical complexity of the lignite molecule and its reactions, it ispreferred to describe this type of product as the reaction product oflignite, a sulfite and an aldehyde or ketone in a basic reaction medium.The term sulfo-alkylated lignite will be used herein to describe such aproduct, the alkylated part of the term being as above defined.

Lignite is found in many parts of the United States. It is defined as avariety of coal intermediate between peat and bituminous coal,especially one in which the texture of the original wood is distinct. Itis also called brown coal or wood coal. its chemical characteristics andcomposition have been widely described in the literature, such as in theJournal of the American Chemical Society, Vol. 69 (1947), and in the US.Bureau of Mines Information Circular 7691, parts 1 and 2, publishedJuly, 1954. Lignite is to be sharply distinguished from lignin andquebracho, neither of which will yield a dispersant of improvedproperties when substituted for lignite in the process of thisinvention. This is understandable when it is understood that these threesubstances are of quite different chemical nature. Thus,

lignin consists only of carbon, hydrogen and oxygen while lignitecontains also nitrogen and sulfur. Lignin contains no fatty componentswhereas lignite does. Recent research' has yielded conclusive evidencethat lignite is derived primarily from seeds (cones) of the originalgymnosperms rather than from the holes or branches or needles, where aslignin is derived primarily from the holes or branches or needles andnot from seeds. Further, as will be shown hereafter, thesulfo-alkylation of lignin and quebracho, whether or not followed byoxidation, does not materially improve the dispersing properties ofthese materials; in fact, it will sometimes cause these properties todeteriorate.

In general, the term lignite will be used herein to mean not onlylignite per se but also all naturally occurring carboniferous mineralscontaining 10 percent or more, preferably 30 to 50 percent, of humicacid.

The alkali metal hydroxide employed in the sulfoalkylation reaction canbe sodium, lithium or potassium hydroxide. The amounts to be used can bevaried over a considerable range. Its principal function is thought tobe to impart suificient initial solubility to the raw lignite that itcan react with the sulfite and aldehyde or ketone reactants. Thus it hasbeen found that in order to achieve a practical reaction rate for thesulfo-alkylation reaction, the pH of the reaction medium should be atleast 10. In any event, enough hydroxide shouldbe used so that theinitial pH of the reaction medium is at least 7 and preferably 10 to 13.Hence, the reaction can be described as being conducted in a basicreaction medium and it is immaterial whether the hydroxide is separatelyadded to the medium, in admixture with other materials or is alreadypresent therein. When 'a bisulfite (e.g., sodium hydrogen sulfite) isused, suflicient hydroxide should be present to convert this to thesulfite form. It is preferred that the amount of alkali metal hydroxideused be within the range of 10 to parts by weight per 100 parts byweight of the raw lignite. The alkali metal hydroxide can be pro-reactedwith the lignite before the sulfite and aldehyde or ketone are broughtinto the reaction, or it can be added with the latter. In thisconnection, commercial alkali lignite can be used as a starting materialinstead of raw lignite. In some cases, it is desired that the finallignite product have a certain causticity. Thus, in using the instantlignitic derivatives as mud thinners, it has been found that optimumresults are frequently obtained when a certain amount of caustic ispresent. For example, in treating simple aqueous dispersions of clays,optimum results are achieved when about 10 percent by weight ofadditional caustic, based on the weight of the sulfoalkylated ligniteproduct, is added. In lime base muds, this figure is about 20 percent ofadditional caustic. The caustic to be used can be selected from theaforesaid range of 10 to 100 parts per 100 parts of raw lignite to givethe desired degree of causticity to the final dry product so that whenthe dry product is mixed with the mud or other well fluid, the latterhas the desired causticity. Alternatively, an amount of caustic in thelower part of the range, and less than that desired in the final dryproduct, can be used during the sulfo-alkylation reaction. Then theadditional caustic required to yield the final desired causticconcentration can be added to the sulfo-alkylated product, the onlyrequirement being that the caustic be intimately mixed with the lignitereaction product. The final product can be dried by conventionalmethods. The dry product is still free flowing, non-hygroscopic andsubstantially non-corrosive to the skin. In effect then, theligniteproduct masks the caustic, rendering it incapable of doing damagewhen the dispersant-caustic mixture is used in its intended manner.

The above applies not only to the use of the sulfoalkylated product ofthis invention but also to the use of the oxidized derivatives thereofas disclosed herein.

The alkali metal sulfite can be sodium, potassium or lithium sulfite orbisulfite. In general, sulfurous acid and its water-soluble salts alsocan be used. In this connection, the addition of a bisulfite orsulfurous acid to the basic reaction medium will convert the bisulfiteor acid to a sulfite. Hence, the term sulfite will be used herein toinclude the bisulfite as well as other compounds which, when added tothe basic reaction medium, will in effect react as an alkali metalsulfite.

The amount of sulfite to be used will be dependent upon the percentageof lignite desired to be converted to the sulfo-alkylated form. About 25parts of sodium sulfite are required to secure approximately totalconversion of 100 parts of raw lignite and is therefore thestoichiometric equivalent for the sulfo-alkylation reaction. As will bedemonstrated in the examples, use of excess suifite over thatstoichiometrically required to convert the lignite is not harmful to thereaction but is wasteful of sulfite. Generally, it is desired that atleast 6 parts of sulfite be used per 100 parts of lignite. The numericalrange can be stated to be from 6 to 50 parts of sulfite per 100 parts oflignite, it being understood that at the lower limit, the lignite willnot be completely converted and at the upper end of the range, unreactedsulfite will remain in the reaction product. For optimum results, thestoichiometric equivalent of sulfite should'be used.

The aldehyde or ketone employed in the reaction can be any type ofaldehyde or ketone having at least one aldo (HCO) or methyl keto (CH CO)group per molecule so that the aldehyde or ketone has a carbon atomcapable of becoming a methylene or a substituted methylene group in thesulfo-alkylation reaction. Both water-soluble and water-insoluble onescan be used. In general, then, the aldehyde or ketone reactant can berepresented by the formula (RCO),,R where R is chosen to be hydrogen forthe aldehydes and a methyl group for the ketones, n is a whole number ofl to 3 inclusive and R being nonfunctional in the reaction, can be anyaliphatic, alicyclic, aryl or heterocyclic group. Thus, within thisdefinition, aliphatic, alicyclic, aryl and heterocyclic aldehydes andketones, and mixtures thereof, all may be used. For example, alkyl,alkenyl, alkynyl monoand poly-aldehydes and monoand polymethyl ketonescan be used and exempl ry of trese are methanal (including the para formwhich is preferred), 'ethanal, propanal, butanal, hexanal, decanal,dodecanal, tetradecanal, hexadecanal, eicosanal, dotricontanal,acrolein, propenal, butenal, heptenal, decenal, hexadecenal, eicosenal,dotricontenal, propargylaldehyde, butynal, decynal; the correspondingketones with the carbonyl group inthe alpha position (except of coursethat there is no ketone corresponding to methanal, etc.) such asZ-propanone (acetone), Z-butanone, Z-eicosanone, etc; the correspondingdiand tri-aldehydes and the diand tri-ketones (with at least onecarbonyl group in the alpha positionit is not necessary that allcarbonyl groups be so positioned), such as glyoxal, glutaraldehyde,adipialdehyde, arachicaldehyde, 2,4-pentanedione, 2,4- and2,5-hexanedione, 2,15-hexadecanone, 2,5-hexenedione, etc. Representativeof the alicyclic aldehydes and ketones is cyclohexanal, cyclobutanal,cyclooctanal, cyclononal, methyl cyclobutyl ketone, methyl cyclohexylketone, methyl cycloheptyl ketone, methyl cyclononyl ketone, etc. Amongthe aryl aldehydes can be mentioned benzaldehyde, salicylaldchyde,vanillin, cumic aldehyde, cinnamic aldehyde, etc. Furfural can be namedas representative of the heterocyclic aldehydes. Among the aryl ketonesmay be mentioned acetophenone, benzalacetone, etc.

It is notbelieved necessary to further burden the application by listingspecific ones of operable aldehydes and ketones because such can bereadily discerned once it is realized that the reaction of thisinvention is operable with any aldehyde or ketone having one or more 6aldo or methyl keto, or both, groups per molecule. Nevertheless, it isto be realized that the sulfo-alkylated products will vary one from theother in their properties depending somewhat upon the nature of thealdehyde or ketone used in the reaction. For example, it has been foundmost desirable to use formaldehyde or acetaldehyde for producingadditives to be used in well fluids because the other aliphaticaldehydes seem to produce products which cause foaming of the wellfluid. However, even with such foaming products, well-known defoamingagents could be added to the mud to control the foaming. The tendency tofoam has not been noted with furfural or with the ketones or with thearyl aldehydes. For preparing a dispersant for use in wells, it isgreatly preferred to use formaldehyde not only because of its cheapnessand availability but because it yields a product having somewhatsuperior properties as a yield control or thinning agent for muds.

The amount of aldehyde or ketone, like the sulfite, is preferably thestoichiometric equivalent required to completely react the lignite. Ithas been found that approximately twelve to twelve and one-half parts offormaldehyde are required to substantially convert the lignite to thesulfo-methylated form. Stated as a numerical range, the formaldehyde canbe used in the amount of 3 to 25 parts per 100 parts of lignite.

As for the ketones and the aldehydes other than formaldehyde, many ofthem can be used in amounts within the above-specified range to obtainoperable results. However, it is preferred to use amounts which arestoichiometric equivalents for substantially complete reaction of thelignite. Accordingly, the weight of the other aldehyde or ketone usedshould preferably be that which is stoichiometrically equivalent to thelignite or to the formaldehyde as above disclosed. For convenience indefining a range, the amount of aldehyde or ketone of any type to beused in this reaction will be specified herein as an amountstoichiometrically equivalent to an amount of formaldehyde within therange of 3 to 25 parts of formaldehyde per 100 parts of lignite.

It has been found that excess of aldehyde or ketone over thestoichiometric equivalent does not harm the reaction, but results inwaste of material. Use of less than stoichiometric amounts results inless than 100% conversion of lignite.

It will of course be seen from the above that mixtures of the variousaldehydes and ketones can be used to obtain various results.

The reaction medium can be any fluid which is substantially inertinsofar as the reaction is concerned and preferably is water.

The sulfo-alkylation reaction proceeds best at elevated temperatures. Itcan be carried out in simple refluxing equipment at temperatures withinthe range of to 212 F. However, the degree of conversion of the lignitewithin this temperature range is not complete within commerciallyfeasible time limits such as 3 to 7 hours. It is accordingly preferredthat the sulfoalkylation reaction be carried out in pressure vessels attemperatures within the range of 275 to 375 F. At these temperatures,the time of reaction for substantially complete conversion of thelignite will usually fall within the range of l to 6 hours. Stated inanother manner, the lower limit of the temperature range is ratherflexible but should be high enough to give the desired degree ofconversion within the desired time. Of course, lengthening the reactiontime permits lowering of the reaction temperature to give the sameconversion. On the other hand, the upper limit of the temperature rangeis dictated by the maximum temperature which the lignite will toleratewithout serious disruption of its large molecules and consequentdeterioration of the protective colloidal action of the sulfo-alkylateproducts. Approximately 360 to 375 F. represents a workable maximumwhich will not cause substantial degradation of the lignite in aqueoussolution.

the different sulfo-alkylated lignites.

- alysts can be used.

be placed directly in the autoclave and subjected to the elevatedtemperature from the beginning. However, in such case, closer control isrequired and the reaction may not proceed so smoothly as when themixture is refluxed before being autoclaved.

The reaction product can be used in liquid form as it comes from thereaction, but preferably it is dried first. V

Such drying can be accomplished by conventional procedures such as bydrum drying or spray drying at a temperature in the range of 215 to 375F. The dried solids can then be bagged and shipped to the field for useThe dried product, when bagged in conventional multi-wall bags, remainsdry and free-flowas described above.

ing over long periods of storage and will not cake. It is not noticeablycorrosive to the skin and can thus be handled with safety. It can beadded to the mud as a single thinning or dispersing additive by simplypouring it into a mud stream or otherwise admixing it therewith. Sinceit exhibits a marked solubility in water, little or no difliculty willbe encountered in getting it into solution where it can be active toexert its protective colloidal properties.

As indicated above, it has been found possible to increase thehydrophilic properties of the sulfo-alkylated product and to increaseits resistance to calcium and salt, as well as to improve its dispersingpowers in a mud, by oxidizing or nitritating the same. term oxidationshall be used in its broadest sense to include reaction with oxygen,chlorine, nitrites, hydrogen peroxide, hypochlorites, etc. The increaseddispersing efliciency of the oxidized product is particularly notable indrilling muds containing hydratable clays, such as bentonite, and othertypes of muds, such as lime base muds, which exhibit very high yieldpoints prior to adding a dispersant thereto.

The starting material for the oxidation reaction can be any of thesulfo-alkylated lignites disclosed above, but it should be noted thatthe increase in efficiency brought about by the oxidation reaction willvary in degree with For example, a maximum increase in efiiciency seemsto be secured with sulfo-alklated lignite prepared from formaldehyde orfurfural.

There is a wide variety of oxidizing agents which can be used. Thus, anyoxidizing agent which has an effective oxidation potential 1n a reactionmedium, such as As used herein, the

Water, over the alkaline range of pH 7' or above is operable. reasons),is the preferred oxidizing agent. Others include chlorine gas, alkalimetal nitrites, the alkali metal hypochlorites, hydrogen peroxide andothers. Ozone can also be used and it is particularly eflicient becauseof its high oxidation potential and oxidative catalytic power.

While the oxidation reaction proceeds in the absence of a catalyst, itis preferred to use a suitable catalyst to speed up the reaction.Various ones of well-known cat- It should be an oxygen-containingcompound of a polyvalent metallic element known to have more than onevalence toward oxygen. For example, manganese may have valences of 2, 4,6 or 7, while vanadium may have valences of 2, 3, 4 or 5. It isdesirable, but not absolutely essential, that the oxygencontainingcompound of the polyvalent metallic element be capable of becoming thenegative component of an alkali metal salt having at least a moderatesolubility in water over the alkaline pH range; For example, manganesedioxide is almost insoluble in neutral watery suspension but formsmanganites, manganates and permanganates which are reasonably soluble inwater. Likewise, vanadium may enter into the negative component asammonium or alkali metal vanadates or as the alkali metal salts ofvanadous acid and of the other acids with vanadium in still othervalence states. In addition to the oxygen-containing compounds ofvanadium and manganese, there may be mentioned the oxygen-containingcompounds of copper, chromium, molybdenum, selenium, tellurium,tungsten, cerium, arsenic, antimony, iron, cobalt, and nickel. Catalystswhich are preferred, primarily for economic reasons, are cobalt acetateand also manganese dioxide promoted with ammonium metavanadate. Theamount of catalyst to be. used will be de termined primarily by economicconsiderations, that is, the cost of the catalyst per se, the amountrequired to be used to obtain the desired reaction in a minimum of time,etc. The amount used is not critical as long as enough is present tospeed upthe reaction so that it will be completed in the desired time.In the case of the manganese dioxide-ammonium meta-vanadate combination,the amount of manganese dioxide can be within the range of between to 5%of the weight of the sulfo-alkylated lignite being oxidized and theamount of ammonium meta-vanadate equal to approximately to A the weightof the manganese dioxide. An amount of cobalt within the range of thatgiven above for the manganese dioxide can be used. The same rangeapplies to other catalysts. However, it must be emphasized (1) that theoxidation reaction can proceed without a catalyst, (2) that the amountof catalyst used is not important except excessive amounts are expensiveand insufficient amounts may not cause the reaction to be completed in adesired time, and (3) the type of oxidation catalyst may be chosen fromthose known to the prior art.

The oxidation reaction can be carried out in various manners. Thesulfo-alkylated lignite or starting material should be in admixture witha suitable reaction medium,

such as water, the mixture having a pH on the alkaline side. Catalyst,if used, can then be added to this mixture followed by the addition ofthe oxidizing agent. When air is used, it is preferably bubbled throughthe reaction mixture so as to assure that reactive oxygen is dissolvedin the reaction medium. Chlorine can be used in the same way, but itshould be noted that chlorine is very much more reactive than air sothat it should be added to the reaction mixture at a lesser rate. Otheroxidizing agents, such as the nitrites, hydrogen peroxide and the likecan be added in the same manner or the total required amount added atthe initiation of the reaction.

The pressure at which the oxidation reaction is conducted can vary overwide limits although usually atmospheric pressure will be preferred.

The temperature at which the oxidation reaction is conducted can alsovary considerably, but should be below the temperature which thesulfo-alkylated lignite vw'll tolerate without serious disruption of itsmolecule with I a consequent deterioration of its protective colloidalproperties. Approximately 360 to 375 F. represents a workable maximum.However from a practical standpolnt, a temperature within the range of40 to 212 F., preferably to F. can be used. Where the reactron iscarried out at superatmospheric pressure, the range can extend as highas 350 F. Thus the broad range can be stated as 40 to 350 F.

The reaction time and temperature are adjusted to each other in mannerswell-known to those skilled in the art so that the oxidation reactionwill proceed to a point such that the oxidized product has a desiredincrease in its beneficial properties. In other words, thesulfo-alkylated product oxidized to an extent such as will increase itshydrophilic properties. One way of easily determining the optimum timeand temperature conditions is to merely sample the reaction mixtureafter various time and temperature reaction cycles and then determinethe efficiency of the samples by routine tests, such as by using mudsamples.

It has been noted that during the oxidation reaction, the pH of thereaction mixture will decrease and for air oxidation, 2. drop of about 1pH unit will indicate the oxidation reaction has proceeded far enough.Thus, the pH will usually drop from about 10.5 or 11 to about 9.5 duringair oxidation and to even lower values (e.g. 8) during chlorination.Hence, the oxidation should proceed until the pH of the sulfo-alkylatedlignite solution has dropped at least 0.5 unit. Another way of definingthe extent of operable oxidation is to state that the sulfoalkylatedlignite is oxidized until it increases at least 3, preferably from 3 to25, percent in weight. Generally an oxidation time of from 0.5 to 10hours will suflice and the exact value chosen from this range willdepend on the oxidation temperature, catalyst, oxidizing agent and itsconcentration, extent of agitation and other factors.

To further demonstrate the invention, the following examples are setforth:

EXAMPLE I A sulfomethylated lignite sample was prepared by mixingtogether 30 parts of water, 8 parts of lignite, 2 parts each of sodiumhydroxide and sodium sulfite, and 1 part of para-formaldehyde. Themixture was refluxed at 203 to 212 F. for approximately 3 hours and thenautoclaved for about 5 hours at 296 to 314 F. The resulting product wasdrum dried and denoted as MP-32. To evaluate MP-32 as a simpledispersing agent for drilling muds, a 7 /2 weight percent dispersion ofbentonite in fresh water was made up. Increasing portions of MP-32 wereadded to the mud and its yield point determined. The results are shownin FIG. 1.

In order to compare the effectiveness of MP-32 with other dispersants,other samples of the bentonite dispersion were treated with variousamounts of caustic-dispersant solutions as indicated in FIG. 1. In thisfigure, the weight ratio of caustic to dispersant for each curve isfollowed by the identification of the caustic-dispersant mixture used.

From FIG. 1, it will be sen that MP3=2 is superior to the alkali ligniteand is at least comparable to causticquebracho in its effectiveness.

EXAMPLE II To compare the effectiveness of sulfo-methylated lignite withalkali lignite in lime base muds, the following dispersants wereprepared:

MP13.2OO parts of lignite were refluxed with 27.5 parts of sodiumhydroxide for about 5 hours. 50 parts of sodium sulfite followed by 25parts of paraformaldehyde were then added. The mixture was refluxed at203 212 F. for 5 hours.

MP-23.The same procedure was followed as for MP-13 except that 50 partsof sodium hydroxide were used.

MP17.20O parts of lignite were refluxed with 27.5 parts of sodiumhydroxide for 5 hours at 203212 F.

Three pounds per barrel of the various dispersants (calculated on awater-free basis) and three pounds per barrel of caustic were added tosamples of a 7 /2 weight percent suspension of bentonite in fresh water.Increasing increments of lime were then added to the samples and theiryield points determined. The results are shown in FIG. 2.

As will be seen from this figure, the sulfo-methylated lignite ismarkedly superior to conventional alkali lignite. Also, increasing theamount of sodium hydroxide in the sulfo-methylating reaction resulted ina somewhat superior product.

EXAMPLE III The MP-l7 and MP-23 dispersants of Example II, as well asMP-24 (prepared the same as MP-23 except the autoclaving temperature was360-370 F.), were each added in increments to samples of a 7 /2 weightpercent bentonite suspension. The yield points were determined til aftereach addition. When 2 lb./bbl. of each dispersant had been added to itssample, salt (sodium chloride) was then added in increments and theyield point determined after each addition. The results are shown inFIG. 3.

It will thus be seen that the sulfo-methylated lignite not only issuperior to alkali lignite in lime base or calciumcontaminated muds butalso in salt-contaminated muds.

EXAMPLE IV To show that each of the alkali metal salts ofsulfomethylated lignite are operable to give the advantages of thisinvention, MP-40 and MP-41 were prepared. The procedure of preparationwas the same as for MP-23 recited above except that equivalent amountsof lithium hydroxide and lithium sulfite were substituted for thecorresponding sodium compounds of MP-23 in preparing MP-40. Similarly,potassium compounds were substituted in preparing MP-4l.

Various amounts of MP-23, MP-40 and MP-41 were added to samples of a 7/2 weight percent bentonite suspension and the yield points determined.Sodium chloride was added in increments to the bentonite suspensionsamples which contained 3 lb./bbl. of the respective dispersants. Theresults are plotted in FIG. 4.

It will be seen that lithium, sodium and potassium compounds areinterchangeable in preparing the dispersant of this invention but thesodium compounds will usually be preferred because of their relativecheapness.

EXAMPLE V The effect of varying the amount of sulfite and aldehyde usedin the sulfo-methylating reaction is shown in FIG. 5. The MP-23 is thesame as that used in Example II. The MP23 /2 and MP-23Mt were preparedin the same manner as the MP-23 except that approximately /2 and A asmuch sodium sulfite and paraformaldehyde were used, respectively. Again,a 7 /2 weight percent bentonite suspension was used. After 3 lb./bbl. ofdispersant had been added to the respective mud samples, lime was addedin increments without the addition of additional caustic; hence, thehump at low lime concentrations. Yield points were determined after eachaddition to the mud.

While MP23 gave the best results in the lime muds at higherconcentrations of lime, it will be seen that all three dispersants areabout equally ellective in the absence of lime.

EXAMPLE VI FIG. 6 shows the effect of varying the amount of sodiumhydroxide used in the sulfo-methylating reaction. The MP-23 and MP-13were the same as in Example 11 while the MP37 was prepared in the samemanner except parts of sodium hydroxide were used. The mud samples were7 /2 weight percent bentonite suspensions. No additional caustic wasadded with the lime. The testing procedure was the same as in Example V.

From FIG. 6, it can be seen that generally the effectiveness of thedispersant in lime muds increases with the increasing amount of sodiumhydroxide used in its synthesis. However, all of the dispersants areusable, with perhaps slightly more of the MP-13 and MP-23 being requiredto give the same results as MP-37 at the higher lime concentrations. Thecost of the increased amounts of MP-13 and MP-23 may be partially orwholly olfset by the extra cost of the additional amount of sodiumhydroxide used in preparing the MP-37.

EXAMPLE VII To determine the effect of sulfo-methylating quebracho, 200parts of quebracho extract (dry, 70% tannin), 50 parts of sodiumhydroxide, 50 grams sodium sulfite and 25 grams of paraformaldehyde and1675 parts of water were stirred together and refluxed for 5 hours at203212 F. This was followed by autoclaving for 5 hours at 296 to 314 F.The resulting product (MP-50) was tested 1 1 in various muds as shown inTable I. MP-32, prepared as in Example I, and caustic-quebracho werealso tested for comparative purposes.

Table I Dispersant Base treating stock mud: Yield 2 lb./bbl. MP-50 18 2lb./bbl. MP-32 9 2 1b./bbl. quebracho; 1 lb./bbl. caustic 12 7 /2 weightpercent bentonite suspension:

2 lb./bbl. MP-SO 17 2 lb./bbl. MP-32 12 2 lb./bbl. quebracho; 1 lb./bbl.caustic 13 From the foregoing it can be seen that quebracho which hasbeen treated in the same manner as lignite with sulfite and aldehyde isnot rendered-equivalent thereto. In fact, it is inferior to bothsulfo-methylated lignite and to conventional caustic-quebracho as adispersant.

EXAMPLE VIII To demonstrate the range of concentrations of sodiumhydroxide, sodium sulfite and paraformaldehyde which can be reacted withlignite to achieve the benefits of this invention, the tests reported inTable II were run. In each test, the amounts of the indicated reactantswere stirred into Water and the mixture refluxed for five hours at203-212 F. In some cases, the mixture was autoclaved for five additionalhours at the temperature indicated. The final product was then analyzedand the percentage of sulfite and aldehyde reacted was calculated.

Table II Reactants, parts Percent Product Auto- Percent paradispersautclaving, sodium fordesignation Lig- Sodium Para- F. sulfite maideniteNaOH sulfite formalreachyde dehyde ted* reaeted* 200 50 100 50 None 178. 5 200 50 100 50 296-314 24. 5 12. 3 200 27. 5 50 25 None 14. 8 7. 4200 27. 5 50 25 296-314 23. 3 l1. 7 200 27. 5 50 25 360-370 24. 3 12. 2200 50 50 25 296-314 24. 12. O 200 50 25 13 296-314 12. 2 6. l MP23V 20050 13 7 296-314 6. 1 3. 1

*Based upon weight of raw lignite (containing 4 to percent of water).From Table II, it can be seen that autoclaving (re- I action attemperatures substantially above 212 F. but

fite and paraformaldehyde which can be reacted with the North Dakotalignite used at temperatures below the decomposition temperature of suchlignite is about 2425% and 12-12.5% respectively.

EXAMPLE IX 400 parts of lignite, 100 parts each of sodium hydroxide andsodium sulfite and 50 parts of paraformaldehyde were combined with 1510ml. of water and refluxed for 5 hours at 203212 F. Thereafter, themixture was autoclaved for 5 hours at 296-3 14 F. Then the re-- actionmixture was dried and weighed. Each 100 ml. of mixture yielded 26.2grams of dry solids. This is equivalent to a yield of dry solids of 87.3weight percent of the dry reactant starting materials. Calculationsbased on the theoretical reaction and taking into account the MP-32dispersant requires, as starting reactants, about:

70.6 parts lignite 17.7 parts sodium hydroxide 17 .7 parts sodiumsulfite 8.8 parts paraformaldehyde EXAMPLE X A 10% aqueous solution ofMP-32 (prepared as per Example I) was mixed with 1% (based upon the drysolid MP-32) of ground manganese dioxide and 0.10% ammoniummeta-vanadate (based upon weight of manganese dioxide). The resultingmixture was placed in a Cavitator and air bubbled therethrough atatmospheric pressure. The oxidation caused a mild temperature peak (87F. with an eventual drop nearly back to room temperature). The totaloxidation time was 12 hours. The air-oxidized solution was oven-dried at230 F., ground, bottled and labelled MP-69. The dry product weighedapproximately 12% more than the weight of the original dry MP-32. The pHof the solution dropped approximately 1 pH unit during the oxidation.

The MP-69 was then tested in base stock and in a lime base mud. Theresults are reported in Table III.

Table III BASE STOCK Thinner App. Yield 10 min.

vise. gels 21b./bb1. MIR-69 22. 5 '11 35 2 lb./bbl. quebrach0+1lb./bbl.N aOH 28 12 33 LIME BASE MUD (6 lb. lime per bbl) 5 lb./bbl. MP-69-l-1lb./bbl. NaOH 29 8 35 3 lb./bbl.quebracho+3 lb./bbl. NaOH" 28, 5 9 134From Table III, it would seem that MP-69 is at least as good asquebracho and caustic for thinning simple mud systems and is actuallysuperior in lime base muds because of the much lower 10 minute gel.

EXAMPLE XI A series of different sulfo-alkylated lignites were preandthen various amounts of the aldehydes and ketones indicated in Table IVwere added. The reaction was allowed to continue for approximately-5hours at approximately 200212 F. and atmospheric pressure. Thereafter,the mixture was autoclaved for 5 hours at a temperature in the range of275-315" F. Where the reaction product was not to be oxidized, themixture was then removed from the autoclave and dried. Where the mixturewas oxidized, this was accomplished by bubbling air therethrough forapproximately 7 hours at about 120 F. A catalyst comprising one part ofmanganese dioxide and .2 part of ammonium meta-vanadate was used.

In each reaction, there was a significant decrease in pH of the mixtureduring both the sulfo-alkylation reaction and the subsequent oxidation.In most cases the pH dropped from the order of 12 for the initialmixture to 9 or 10 for the final oxidized mixture. Each reaction yieldedat least of theoretical and there was increase in weight of from 5 toabout 15% (based upon the sulfoalkylated product per so) during theoxidation reaction. Each product upon drying remained dry andfree-flowing and was not corrosive to the skin.

The various reaction products were tested in drilling muds. For, thecolumn labelled WBM (Water base mud) the mud comprised about 15 lb./bbl.of Yellowstone bentonite, 31 1b./ bbl. of a low yielding adsorptive clay(X-act) and 73 lb./bbl. of barite, thus giving a mud having 25.4% solidsby weight and a weight of 1 0.3 p.p.g. The lime base muds (LBM) weremade by adding 6 lb./bbl. of lime to the water base muds. For the teststo determine the yield point or" the water base mud, 2 lb./bbl. of thereaction product (thinner) were added. For the tests for the lime basemud, 5 lb./bbl. of the thinner plus 1 lb./bbl. of caustic were added.

Table IV Yield point Reaetant-pts.lwgt. Oxidized I WBM LBMGlutaraldehyde-26 N o 8 24 Acrylic aldehyde-2L Acetone25 Methyl ethylketne-31 Hexane dime-42 Methyl isobutyl ketone Acet0phcnone4l C -l2 Benzaldehyde-Zl B enzaldehyde-2l Salicylaldehyde-2 Salicylaldehyde26 Theabove test clearly demonstrate the thinning action of the variousreaction products, particularly when it is considered that the waterbase mud, in the absence of a thinner, had a yield point ofapproximately 70 or more.

- The yield point of the lime base mud, without thinner,

Sulfo-methylated lignite (MP-32) was oxidized by nitration. Toaccomplish this, 850 parts by weight of MP-32. solids were placed inwater along with 25 parts by weight of sodium nitrite. The mixture wasrefluxed for hours at 200212 F. and then dried to constant weight at 230F. During the oxidation, the MP32 solids increased approximately 3 inweight. Comparative tests of the oxidized (nitrated) product (thinner)(3 lb./bbl. of thinner), the original sulfo-methylated lignite andquebracho-caustic (-5) in a lime mud showed that the yield point of themuds containing the nitrated product Was only A of the yield point ofthe muds containing sulfo-methylated lignite or the quebracho-causticproduct. A comparison of the nitrated product and MP-69 (airoxidizedsulfo-methylated lignite) at a level of 5 lb./bbl. in the lime base mudindicated the yields of the mud were approximately the same and in eachcase were 6 or less.

EXAMPLE XIII To demonstrate that hydrogen peroxide could be used as theoxidizing agent, 1000 parts of sulfo-methylated lignite (MP-32) solution(30% MP-32 solids) were oxidized with 120 parts of 30% hydrogen peroxideadded over a period of 1.5 hours. In one test, 23 parts of ammoniummeta-vanadate (plus 8 parts of additional NaOH) was used as a catalystand in the other 50 parts of cobalt acetate tetra-hydrate (plus 16 gramsadditional NaOH) was used as a catalyst. In each case, the reaction wasconducted at about 175 F. and at atmospheric pressure.

During the oxidation, the pH of the mixture dropped 14- approximately 1unit and there was a noticeable decrease in viscosity and a typical gainin weight of the MP-32.

Tests of the oxidized products in water base muds as above definedreduced the yield point (at 2 lb./bbl. of the oxidized product) to about30% of that of the untreated mud.

EXAMPLE XIV As pointed out above, the sulfo-alkylated lignites of thisinvention can have their eificiency increased by using chlorine (orequivalent) as the oxidizing agent. To demonstrate this, a solution ofsulfomethylated lignite (MP- 32) was vigorously agitated while amoderate stream of chlorine gas was passed thereinto. As thechlorination proceeded, the temperature of the charge rose about 20 F.within one hour, while the pH dropped from an original 10.6 to 7.0. Thechlorination was interrupted after one hour. The rapid drop in pH andrise in temperature indicated a vigorous oxidation of thesulfa-methylated lignite by the chlorine. At this point it should bepointed out that since the oxidation was conducted in an alkalinemedium, the chlorine probably was converted to sodium hypochlorite andthis was actually the oxidizing agent. However, Whether sodiumhypochlorite, chlorine gas or other halide yielding materials are used,the over all process can be called oxidation.

Tests of the chlorinated product in a lime base mud (6 lb./bbl. lime),using 4 lb./bbl. of the product with 2.5 lb./bbl. of caustic, reducedthe yield point of the mud to 7 from a value which would have been toothick to measure without the thinner. It should be noted that sincefinal pH of the chlorinated product is somewhat lower than that for theair-oxidized product (MP-69), it may be advisable to use additionalamounts of caustic in the mud to compensate for this.

All parts referred to herein are parts by weight unless otherwisespecifically noted. All test procedures used in conjunction withevaluating the various dispersants in drilling muds were conductedaccording to A.P.I. Code 29 and yields are reported in pounds per squarefeet.

As indicated above, the dispersing agents of this invention are usefulnot only in simple water-base muds, but more particularly in mudscontaminated with calcium and sodium compounds which tend to increasethe viscosity of the mud. The amounts of these compounds required tocause an increase in viscosity in the absence of the viscosity reducingagents of this invention will vary with the mud composition and type andthe conditions of its use. Accordingly, no hard and fast rule can belaid down as to the amounts of these contaminants which will cause asubstantial increase in yield and, as is usual in the mud treatment,such mud will have to have its individual tolerance to these compoundsdetermined before any reliable conclusion can be drawn as the yieldpoint increasing amounts of these contaminants. Ordinarily, at least 0.5lb./bbl. of these contaminants will be required to tend to cause asubstantial increase in yield. It should further be pointed out that thethinning agents of this invention are especially useful in lime basemuds where lime is deliberately added along with caustic in a mannerwell-known to those skilled in the art.

The exact amounts of the thinners which are to be added to a particularmud to reduce its yield to a desired value can only be determined in thefield by routine tests. As is known, these tests are conducted on mudbefore it is thinned even when well-known thinners such ascausticquebracho are being used. However, for the sake of completeness,it is stated that the dispersing agents of this invention can be used inamounts within the range of 0.5 to 15, preferably 1 to 10,lb./bbl. toachieve various degrees of thinning in diiferent muds.

Usually the pH of the mud to be treated will be above 7.

From the foregoing it will be seen that this invention is one welladapted to attain all of the ends and objects lected from the groupconsisting of aldehydes and methyl ketones in anamount-stoichiometrically equivalent to an amount of formaldehyde in therange of 3 to 25 parts of formaldehyde per '100 parts of said lignite,the reaction being conducted at an elevated temperature under 375 F.

2. The process of preparing a sulfo-alkylated lignite which comprisesmixing lignite in a fluid reaction medium with 10 to 100 parts of analkali metal hydroxide per 100' parts of said lignite, with 6 to 50parts of an alkali metal sulfite per 100 parts of said lignite and witha methylenic compound selected from the group consisting of aldehydesand methyl ketones in an amount stoichiometrically equivalent to anamount of formaldehyde in the range of 3 to 25 parts per 10 parts ofsaid lignite, maintaining the reaction mixture at an elevatedtemperature below 375.

F. for a period of time sufficient to cause said lignite to be convertedto a more hydrophyllic form and then drying the resulting ligniticreaction product.

3. The process of claim 2 wherein said methylenic compound isformaldehyde.

4. The process for increasing the hydrophyllic properties of lignitewhich comprises reacting lignite in an alkaline reaction medium with asulfur compound selected from the group consisting of sulfurous acid andits watersoluble salts, and a methylenic compound selected from thegroup consisting of aldehydes and methyl ketones to form asulfo-alkylated lignite, and oxidizing the sulfoalkylated lignite in afluid reaction medium with an oxidizing agent having effective oxidationpotential in the fluid medium at a pH not less than 7.0 at a temperaturein the range of 40 to 375 F. and for a period of time sufiicient toincrease the weight of the sulfo-alkylated lignite by at least threepercent, the time and temperature being selected to be such that thedispersing power and the tolerance toward calcium ions in aqueoussolution of the sulfo-alkylated lignite is increased.

5. A dry free-flowing water soluble lignite derivative made by heating100 parts of lignite in a liquid reaction mixture with from 6 to 50parts of alkali metal sulfite, 3 to 25 parts of formaldehyde, and to 100parts of alkali metal hydroxide at a temperature in the range from 175to 375 F. for a time suflicient for a substantial portion of the sulfiteand formaldehyde to react and form side chains on the lignite having theformula RSO M, wherein R-- is a methylene group and M is an alkalimetal; and drying the resulting product.

6. A water soluble lignite derivative made by heating 100 parts oflignite in an alkaline liquid reaction medium with 6 to 50 parts of asulfur compound selected from the group consisting of sulfurous acid andits water soluble salts, and a methylenic compound selected from thegroup consisting of aldehydes and methyl ketones, said methylniccompound being present in amount stoichiometriically equivalent to anamount of formaldehyde within the range from 3 to 25 parts offormaldehyde per 100 parts of lignite, at a temperature in the rangefrom 175 to 375 F. for a time sufficient for a substantial proportion ofthe methylenic and the sulfur compounds to react :and form side-chainson the lignite having the formula --R4O M, wherein R- is selected fromthe group consisting of methylene and substituted methylene radicals andM is an alkali metal; and drying the resulting product.

7. The derivative of claim 6 wherein said methylenic compound isformaldehyde.

8. The derivative of claim 6 wherein the methylenic compound isfurfuryl.

9. The derivative of claim 6 wherein said methylenic compound isacetone.

10. A water soluble lignite derivative made by heating an alkalineliquid reaction mixture containing parts of lignite, 6 to 50 parts of asulfur compound selected from the group consisting of sulfurous acid andits water soluble salts, and a methylenic compound selected from thegroup consisting of aldehydes and methyl ketones, said methyleniccompound being present in amount stoichiometrically equivalent to anamount of formaldehyde within the range from 3 to 25 parts offormaldehyde per 100 parts of lignite, at a temperature in the rangefrom to 375 F. for a time sufficient for a substantial proportion of themethylenic compound and sulfur compound to react with each other andwith the lignite; oxidizing the resulting product sufiiciently'toincrease the yield point reducing power thereof; and drying the product.

11. The process of preparing a sulfo-alkylated lignite which comprisesreacting lignite in an alkaline reaction medium with from 6 to 50 partsof an alkali metal sulfite and from 3 to 25 parts of formaldehyde per100 parts of said lignite, the reaction being conducted at an elevatedtemperature under 375 F 12. The process of preparing a sulfo-alkylatedlignite which comprises reacting lignite in an alkaline reaction mediumwith from 6 to 50 parts of an alkali metal sulfite, and furfural in anamount stoichiometrically equivalent 'to an amount of formaldehyde inthe range of 3 to 25 parts of formaldehyde per 100 parts of saidlignite, the reaction being conducted at an elevated temperature under375 F.

13. The process of preparing a sulfo-alkylated lignite which comprisesreacting lignite in an alkaline reaction medium with from 6 to 50 partsof an alkali metal sulfite and acetone in an amount stoichiometricallyequivalent to an amount of formaldehyde in the range of 3 to 25 parts offormaldehyde per 100 parts of said lignite, the reaction being conductedat an elevated temperature under 375 F.

14. A process for increasing the hydrophyllic properties of lignitewhich comprises reacting lignite in an alkaline reaction medium with asulfur compound selected from the group consisting of sulfurous acid andits water-soluble salts, and a methylenic compound selected from thegroup consisting of aldehydes and methyl ketones to form asulfo-alkylated lignite, and oxidizing the sulfo-alkylated lignite withair in a fluid reaction medium in the presence of an oxidation catalystcomprising an oxygen-containing compound of a polyvalent metallicelement having more than one valence toward oxygen, at a temperature inthe range of 40 to 375 F. and for a period of time sufiicient toincrease the weight of the sulfo-alkylated lignite by at least threepercent, the time and temperature being selected to be such that thedispersing power and the tolerance toward calcium ions in aqueoussolution of the sulfo-alkylated lignite is increased.

15. A process for increasing the hydrophyllic properties of lignitewhich comprises reacting lignite in an alkaline reaction medium with analkali metal sulfite and the tolerance toward calcium ions in aqueoussolution of the sulfo-alkylated lignite is increased.

16. A process for increasing the hydrophyllic properties of lignitewhich comprises reacting lignite in an alkaline reaction medium with analkali metal sulfite and furfural, and oxidizing the sulfo-alkylatedlignite with air in a fluid reaction medium in the presence of anoxidation catalyst comprising an oxygen-containing compound of apolyvalent metallic element having more than one valence toward oxygen,at a temperature in the range of 40 to 375 F. and for a period of timesufficient to increase the weight of the sulfo-alkylated lignite by atleast three percent, the time and temperature being selected to be suchthat the dispersing power and the tolerance toward calcium ions inaqueous solution of the sulfo-alkylated lignite is increased.

17. A process for increasing the hydrophyllic properties of lignitewhich comprises reacting lignite in an alkaline reaction medium with analkali metal sulfite and acetone, and oxidizing the sulfo-alkylatedlignite with air in a fluid reaction medium in the presence of anoxidation catalyst comprising an oxygen-containing compound of apolyvalent metallic element having more than one valence toward oxygen,at a temperature in the range of 40 to 375 F. and for a period of timesufiicient to increase the weight of the sulfo-alkylated lignite by atleast three percent, the time and temperature being selected to be suchthat the dispersing power and the tolerance toward calcium ions inaqueous solution of the sulfo-alkylated lignite is increased.

18. A process for increasing the hydrophyllic proper ties of lignitewhich comprises reacting lignite in an alkaline reaction medium with asulfur compound selected from the group consisting of sulfurous acid andits watersoluble salts, and a methylenic compound selected from thegroup consisting of aldehydes and methyl ketones to form asulfo-alkylated lignite, and oxidizing the sulfoalkylated lignite withchlorine in a fluid reaction medium at a temperature in the range of 40to 375 F. and for a period of time sufficient to increase the weight ofthe sulfo-alkylated lignite by at least three percent, the time andtemperature being selected to be such that the dispersing power and thetolerance toward calcium ions in aqueous solution of the sulfo-alkylatedlignite is increased.

19. A process for increasing the hydrophyllic properties of lignitewhich comprises reacting lignite in an alkaline reaction medium with asulfur compound selected from the group consisting of sulfurous acid andits watersoluble salts, and a methylenic compound selected from thegroup consisting of aldehydes and methyl ketones to form asulfo-alkylated lignite, oxidizing the sulfo-alkylated lignite with awater-soluble nitrite in a fluid reaction medium, at a temperature inthe range of 40 to 375 F.

18 and for a period of time sufficient to increase the weight of thesulfo-alkylated lignite by at least three percent, the time andtemperature being selected to be such that the dispersing power and thetolerance toward calcium ions in aqueous solution of the sulfo-alkylatedlignite is increased.

20. A water-soluble lignite derivative made by heating an alkalineliquid reaction mixture containing 100 parts of lignite, 6 to parts of asulfur compound selected from the group consisting of sulfurous acid andits watersoluble salts, and formaldehyde within the range from 3 to 25parts of formaldehyde per parts of lignite, at a temperature in therange from to 375 F. for a time sufficient for a substantial proportionof formaldehyde and sulfur compound to react with each other and withthe lignite; oxidizing the resulting product sufiiciently to increasethe yield point reducing power thereof; and drying the product.

21. A water-soluble lignite derivative made by heating an alkalineliquid reaction mixture containing 100 parts of lignite, 6 to 50 partsof a sulfur compound selected from the group consisting of sulfurousacid and its watersoluble salts, and furfural in amountstoichiometrically equivalent to an amount of formaldehyde within therange from 3 to 25 parts of formaldehyde per 100 parts of lignite, at atemperature in the range from 175 to 375 F. for a time sufficient for asubstantial proportion of the furfural and sulfur compound to react witheach other and With the lignite; oxidizing the resulting productsufficiently to increase the yield point reducing power thereof; anddrying the product.

22. A water-soluble lignite derivative made by heating an alkalineliquid reaction mixture containing 100 parts of lignite, 6 to 50 partsof a sulfur compound selected from the group consisting of sulfurousacid and its watersoluble salts, and acetone in amountstoichiometrically equivalent to an amount of formaldehyde within therange from 3 to 25 parts of formaldehyde per 100 parts of lignite, at atemperature in the range from 175 to 375 F. for a time sufficient for asubstantial proportion of acetone and sulfur compound to react with eachother and with the lignite; oxidizing the resulting product sufficientlyto increase the yield point reducing power thereof; and drying theproduct.

No references cited.

1. THE PROCESS OF PREPARING A SULFO-ALKYLATED LIGNITE WHICH COMPRISES REACTING LIGNITE IN AN ALKALINE REACTION MEDIUM WITH FROM 6 TO 50 PARTS OF A SULFUR COMPOUND SELECTED FROM THE GROUP CONSISTING OF SULFUROUS ACID AND ITS WATER-SOLUBLE SALTS, AND A METHYLENIC COMPOUND SELECTED FROM THE GROUP CONSISTING OF ALDEHYDES AND METHYL KETONES IN AN AMOUNT STOICHIOMETRICALLY EQUIVALENT TO AN AMOUNT OF FORMALDEHYDE IN THE RANGE OF 3 TO 25 PARTS OF FORMALDEHYDE PER 100 PARTS OF SAID LIGNITE, THE REACTION BEING CONDUCTED AT AN ELEVATED TEMPERATURE UNDER 375*F.
 6. A WATER SOLUBLE LIGNITE DERIVATIVE MADE BY HEATING 100 PARTS OF LIGNITE IN AN ALKALINE LIQUID REACTION MEDIUM WITH 6 TO 50 PARTS OF A SULFUR COMPOUND SELECTED FROM THE GROUP CONSISTING OF SULFUROUS ACID AND ITS WATER SOLUBLE SALTS, AND A METHYLENIC COMPOUND SELECTED FROM THE GROUP CONSISTING OF ALDEHYDES AND METHYL KETONES, SAID METHYLNIC COMPOUND BEING PRESENT IN AMOUNT STOICHIOMETRICALLY EQUIVALENT TO AN AMOUNT OF FORMALDEHYDE WITHIN THE RANGE FROM 3 TO 25 PARTS OF FORMALDEHYDE PER 100 PARTS OF LIGNITE, AT A TEMPERATURE IN THE RANGE FROM 175* TO 375*F. FOR A TIME SUFFICIENT FOR A SUBSTANTIAL PROPORTION OF THE METHYLENIC AND THE SULFUR COMPOUNDS TO REACT AND FORM SIDE CHAINS ON THE LIGNITE HAVING THE FORMULA -R-SO3M, WHEREIN -R- IS SELECTED FROM THE GROUP CONSISTING OF METHYENE AND SUBSTITUTED METHYLENE RADICALS AND M IS AN ALKALI METAL; AND DRYING THE RESULTING PRODUCT. 